Photorefractive Keratotomy is corrective eye surgery that utilizes an excimer laser to change the curvature of the cornea in an effort to correct myopia, hyperopia and astigmatism. Lately, more complex ablation patterns have allowed for the correction of higher order aberrations. A fundamental step during the surgery is symmetric, rapid removal of the central and paracentral corneal epithelium, or skin layer of the cornea, to enable the laser to reshape the corneal stroma. The more consistent a surgeon becomes at this step, the more consistent his or her results will be. The ultimate goal is to remove enough of the epithelium to support the larger diameter of modern day excimer lasers yet not too much as this prolongs the healing time and may increase the risk of infection. Removal of the epithelium can be a very stressful part of the procedure from a patient's perspective, and minimizing the patient's anxiety can improve their ability to follow the surgeon's instructions and maximize the success of the surgical outcome. It is therefore an objective of the present invention to provide means for removing the corneal epithelium that is consistent and less stressful to the patient.
Current techniques and devices used to remove the epithelium include rotating brushes similar to an electric toothbrush that grind away the epithelium. These brushes can pull the eye in different directions adding stress to the patient and may remove too much of the epithelium. Another current technique involves holding a small well on the patient's eye that contains an agent to weaken the epithelium's adhesion to the underlying stroma. This technique can also be stressful to the patient as the surgeon must place a certain amount of pressure on the eye to contain the agent, and if the patient moves their eye, the agent can spill over the eye causing the surgeon to spend additional time cleaning up the spill, which increases surgical time and makes results less consistent. Spillage can also lead to more chronic problems such as, but not limited to, dry eye. Another current epithelial removal technique involves using a sharp blade to debride the epithelium which can cause an irregular surface and ultimately may limit the surgical result.
In view of the foregoing, there is a need for improved techniques for removing the corneal epithelium that enables a user to control the amount of the epithelium that is removed, minimizes the risk of spillage and creates an even surface.
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